//! Provides an implementation of the HotReloadHandler from the `azul_css` crate, allowing CSS
//! files to be dynamically reloaded at runtime.

use azul_css::{HotReloadHandler, Css};
use std::time::Duration;
use std::path::PathBuf;

pub const DEFAULT_RELOAD_INTERVAL: Duration = Duration::from_millis(500);

/// Allows dynamic reloading of a CSS file at application runtime.
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub struct HotReloader {
    file_path: PathBuf,
    reload_interval: Duration,
}

impl HotReloader {
    /// Creates a HotReloader that will load a style directly from the CSS file
    /// at the given path.
    pub fn new<P: Into<PathBuf>>(file_path: P) -> Self {
        Self { file_path: file_path.into(), reload_interval: DEFAULT_RELOAD_INTERVAL }
    }

    pub fn with_reload_interval(self, reload_interval: Duration) -> Self {
        Self { reload_interval, .. self }
    }
}

impl HotReloadHandler for HotReloader {
    fn reload_style(&self) -> Result<Css, String> {
        use std::fs;
        use crate::css;

        let file_name = self.file_path.file_name().map(|os_str| os_str.to_string_lossy()).unwrap_or_default();

        let reloaded_css = fs::read_to_string(&self.file_path)
            .map_err(|e| format!("Error parsing CSS file: \"{}\":\r\nIO Error: {}", file_name, e))?;

        css::new_from_str(&reloaded_css).map_err(|e| format!("Error parsing CSS file: \"{}\":\r\n{}", file_name, e))
    }

    fn get_reload_interval(&self) -> Duration {
        self.reload_interval
    }
}
